Exercise

# Working with statistical aggregate functions

SQL Server offers several aggregate functions for statistical purpose. The `AVG()`

function generates the mean of a sample. `STDEV()`

and `STDEVP()`

give us the standard deviation of a sample and of a population, respectively. `VAR()`

and `VARP()`

give us the variance of a sample and a population, respectively. These are in addition to the aggregate functions we learned about in the previous exercise, including `SUM()`

, `COUNT()`

, `MIN()`

, and `MAX()`

.

In this exercise, we will look once more at incident rollup and incident type data, this time for quarter 2 of calendar year 2020. We would like to get an idea of how much spread there is in incident occurrence--that is, if we see a consistent number of incidents on a daily basis or if we see wider swings.

Instructions

**100 XP**

- Fill in the missing aggregate functions. For standard deviation and variance, use the sample functions rather than population functions.